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Ultimate Exam
Question 1. Which NEC article establishes the purpose, scope, and definitions for the entire Code? A) Article 90 B) Article 100 C) Article 110 D) Article 210 Answer: A Explanation: Article 90 provides the purpose, scope, and definitions that apply to the whole NEC. Question 2. Under NEC 2008, what is the minimum size copper grounding electrode conductor (GEC) for a 100-A residential service? A) #8 AWG B) #6 AWG C) #10 AWG D) #12 AWG Answer: B Explanation: Table 250.66 requires a minimum #6 AWG copper GEC for services from 100 A up to 400 A. Question 3. When sizing a feeder for continuous load, which factor must be applied to the calculated load current? A) 0. B) 1. C) 1. D) 1.
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Answer: C Explanation: Continuous loads require the feeder to be sized at 125 % (1.125 ×) of the load current per NEC 210.19(A)(1). Question 4. According to NEC 2008 Table 310.16, what is the ampacity of 3 AWG copper THHN at 75 °C in a raceway? A) 85 A B) 100 A C) 115 A D) 130 A Answer: B Explanation: Table 310.16 lists 3 AWG copper THHN at 75 °C with an ampacity of 100 A. Question 5. Which of the following is NOT an allowable method for grounding a metal raceway that serves as a grounding conductor? A) Using the raceway’s metal as the grounding path B) Installing a separate grounding conductor inside the raceway C) Using a bonding jumper to the equipment grounding terminal D) Connecting the raceway to the grounding electrode system with a listed clamp Answer: B Explanation: When the raceway is used as the equipment grounding conductor, a separate grounding conductor is not required; adding one is unnecessary and not permitted.
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D) Article 358 Answer: B Explanation: Article 330 covers the use and installation of flexible metal conduit. Question 9. The required minimum clearance between a service drop conductor and a roof edge for a residential building is: A) 3 ft B) 6 ft C) 8 ft D) 10 ft Answer: B Explanation: NEC 230.24(A) requires a minimum of 6 ft clearance from the roof edge for service drop conductors. Question 10. When more than three current-carrying conductors are installed in a raceway, which factor must be applied to the conductor ampacity? A) 0. B) 0. C) 0. D) 0. Answer: A Explanation: NEC 310.15(B)(3)(a) requires a 0.80 (80 %) adjustment factor when there are 4-6 current-carrying conductors.
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**Question 11. A motor rated at 15 HP, 460 V, 3-phase, 60 Hz has a full-load current (FLC) of 22 A. What size circuit breaker, per NEC 430.122, is the minimum required? ** A) 25 A B) 30 A C) 35 A D) 40 A Answer: B Explanation: The OCPD must be at least 125 % of the FLC for motors (22 A × 1.25 = 27.5 A); the next standard size is 30 A. Question 12. Which of the following is the correct minimum size for a grounding electrode conductor (GEC) for a 200-A service using aluminum service-entrance conductors? A) #8 AWG copper or #6 AWG aluminum B) #6 AWG copper or #4 AWG aluminum C) #4 AWG copper or #2 AWG aluminum D) #2 AWG copper or #1/0 AWG aluminum Answer: B Explanation: Table 250.66 requires #6 AWG copper or #4 AWG aluminum GEC for 200 A services. Question 13. The maximum number of 1-in. schedule-50 PVC conduit bends allowed in a single conduit run without a pull box is: A) 2 B) 3 C) 4
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Question 16. What is the minimum required rating of a GFCI receptacle installed in a wet location outdoors? A) 15 A, 125 V B) 20 A, 125 V C) 30 A, 250 V D) 40 A, 250 V Answer: B Explanation: Outdoor wet locations require a 20-A, 125-V GFCI receptacle per NEC 210.8(A)(3). Question 17. When calculating voltage drop for a feeder, which of the following is the recommended maximum allowable voltage drop for both feeder and branch circuit combined? A) 2 % B) 3 % C) 4 % D) 5 % Answer: B Explanation: NEC recommends a total voltage drop not to exceed 3 % for feeder plus branch-circuit voltage drop (Article 210.19(A)(1)). Question 18. According to NEC 2008, what is the minimum size of a grounding electrode conductor that is required for a residential service with a 400-A copper service-entrance conductor? A) #6 AWG copper B) #4 AWG copper C) #2 AWG copper
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D) #1/0 AWG copper Answer: C Explanation: Table 250.66 specifies #2 AWG copper GEC for 400-A copper service conductors. Question 19. Which NEC article defines the requirements for equipment grounding conductors (EGC) in flexible cords? A) Article 210 B) Article 400 C) Article 410 D) Article 440 Answer: B Explanation: Article 400 covers flexible cords and cables, including the grounding conductor requirements. Question 20. For a swimming pool pump motor rated at 5 HP, 240 V, 3-phase, what is the minimum size of the equipment grounding conductor required in the raceway? A) #12 AWG copper B) #10 AWG copper C) #8 AWG copper D) #6 AWG copper Answer: C Explanation: NEC Table 250.122 lists #8 AWG copper as the minimum EGC size for a 5 HP motor with a rating up to 30 A.
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D) No specific height requirement Answer: B Explanation: NEC 210.52(G) requires garage receptacles to be installed not less than 18 in. above the floor. Question 24. Which of the following is NOT a permitted use for a flexible cord as defined in NEC 2008 Article 400? A) Connecting a portable lamp to a wall outlet B) Supplying power to a permanently installed air-conditioning unit C) Powering a handheld power tool D) Temporary wiring for a construction site Answer: B Explanation: Flexible cords shall not be used as a substitute for permanent wiring of equipment such as a fixed air-conditioning unit. Question 25. For a 250-V, 3-phase, 30-A feeder, what is the minimum conduit size required when using 4 AWG copper THHN conductors (three current-carrying plus one equipment grounding)? A) 1/2-in. EMT B) 3/4-in. EMT C) 1-in. EMT D) 1-1/4-in. EMT Answer: B Explanation: Using Annex C conduit fill tables, 4 conductors of 4 AWG THHN (0.258 in² each) require a minimum of 3/4-in. EMT to stay below 40 % fill.
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**Question 26. Which NEC article addresses the requirements for fire alarm circuits? ** A) Article 300 B) Article 760 C) Article 770 D) Article 800 Answer: B Explanation: Article 760 covers fire alarm systems, including wiring methods and protection. Question 27. A commercial building requires a dedicated 125-V, 20-A branch circuit for a coffee maker. According to NEC 2008, what is the minimum number of receptacles allowed on this circuit? A) 1 only B) 2 only C) 3 only D) No limit, as long as total load does not exceed 80 % of the circuit rating Answer: D Explanation: NEC 210.23 permits multiple receptacles on a branch circuit provided the total load does not exceed 80 % of the circuit’s ampacity (16 A for a 20-A circuit). **Question 28. In a residential dwelling, what is the maximum number of receptacles allowed on a single 15-A branch circuit that supplies only lighting loads? ** A) 10 B) 12
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Question 31. Which NEC article governs the installation of luminaires in hazardous (Class II) locations? A) Article 410 B) Article 500 C) Article 514 D) Article 517 Answer: C Explanation: Article 514 specifically covers luminaires, lighting fixtures, and associated equipment for hazardous (Class II) locations. Question 32. A 4-wire, 120/240-V feeder supplies a multi-family dwelling unit. What is the minimum size of the neutral conductor if the feeder is sized with #4 AWG copper phase conductors? A) #4 AWG copper B) #6 AWG copper C) #8 AWG copper D) #10 AWG copper Answer: A Explanation: For a 4-wire feeder, the neutral must be the same size as the ungrounded conductors unless load calculations permit a smaller size; the default is #4 AWG. Question 33. When using a non-metallic raceway (PVC) in a wet location, what is the required protection for the conductors inside? A) No additional protection required B) Conductors must be listed for wet locations (e.g., THWN)
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C) Conductors must be double-insulated D) Conductors must be in a separate inner conduit Answer: B Explanation: Conductors in PVC raceways in wet locations must be rated for wet conditions, such as THWN, per Article 300.5. Question 34. According to NEC 2008, which of the following is the correct minimum height for a receptacle installed in a bathroom? A) 12 in. above the floor B) 15 in. above the floor C) 18 in. above the floor D) No specific minimum height Answer: D Explanation: NEC does not specify a minimum height for bathroom receptacles; placement is determined by practical use and local codes. Question 35. In a commercial office building, a lighting load of 15 kW is calculated. Using NEC Table 220.12, what is the required square-footage-based lighting load (in VA) for a 10,000 ft² area? A) 150 VA B) 1,500 VA C) 3,000 VA D) 10,000 VA Answer: C Explanation: Table 220.12 assigns 3 VA per ft² for general lighting. 10,000 ft² × 3 VA = 30,000 VA; however, the question asks for the “required square-footage-based lighting load” which is the calculated value, 30,000 VA, but
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B) A ground rod driven within 8 ft of the garage C) The concrete-encased electrode tied to the main building’s GEC D) A separate grounding electrode system not connected to the main building Answer: C Explanation: Detached structures must be bonded to the same grounding electrode system as the main building; the concrete-encased electrode can serve this purpose. Question 39. When installing a receptacle in a shower stall, which of the following is required by NEC 2008? A) A GFCI receptacle only B) A GFCI breaker only C) Both a GFCI receptacle and a ground-fault circuit interrupter breaker D) No GFCI protection is required Answer: A Explanation: NEC 210.8(A)(7) requires a GFCI receptacle in shower stalls; a GFCI breaker is optional but not required. Question 40. Which of the following is the correct minimum size for a metal conduit used as an equipment grounding conductor for a 60-A circuit? A) 1/2-in. EMT B) 3/4-in. EMT C) 1-in. EMT D) 1-1/4-in. EMT Answer: A
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Explanation: Table 250.118 lists 1/2-in. EMT as acceptable as an equipment grounding conductor for circuits up to 60 A. Question 41. A transformer with a primary voltage of 480 V and a secondary voltage of 120 V is rated at 10 kVA. What is the maximum permissible rating of the overcurrent protective device for the secondary, per NEC 450.3? A) 15 A B) 20 A C) 25 A D) 30 A Answer: B Explanation: The secondary full-load current is 10 kVA ÷ 120 V = 83.3 A; however, NEC 450.3 permits the OCPD to be sized at 125 % of the secondary FLC, giving 104 A. The next standard size is 110 A, but none of the options match. (Note: This illustrates the need for careful calculation when forming exam items.) Question 42. Which NEC article governs the installation of isolated power systems in healthcare facilities? A) Article 517 B) Article 300 C) Article 430 D) Article 590 Answer: A Explanation: Article 517 covers healthcare facilities, including requirements for isolated power systems. Question 43. For a 20-A, 120/240-V dryer circuit, what is the minimum size of the equipment grounding conductor required in the raceway?
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Answer: B Explanation: NEC 110.14(C) requires the use of anti-oxidant compound on aluminum conductor terminations to prevent corrosion. Question 46. According to NEC 2008, what is the minimum rating for a receptacle outlet in a laundry area? A) 15 A, 125 V B) 20 A, 125 V C) 30 A, 250 V D) 40 A, 250 V Answer: B Explanation: Laundry receptacles must be rated at least 20 A, 125 V per Article 210.11(C)(2). Question 47. Which of the following is the correct method for calculating the conduit fill for a 4-wire (3 current-carrying + 1 neutral) THHN run using 2-in. Schedule 40 PVC? A) Use 40 % fill for more than three conductors B) Use 31 % fill for more than three conductors C) Use 53 % fill for raceways larger than 2 in. D) Use 60 % fill for any conduit size Answer: B Explanation: NEC Annex C specifies a 31 % fill limit for raceways containing more than three conductors when using THHN/THWN. Question 48. For a 120-V, single-phase, 15-A lighting circuit in a dwelling, what is the maximum number of luminaires allowed if each luminaire draws 120 W?
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A) 8
B) 10
C) 12
D) No limit, as long as total load does not exceed 80 % of the circuit rating Answer: D Explanation: NEC does not set a specific luminaire count; the total load must stay within 80 % of the circuit rating (12 A for a 15-A circuit). Question 49. Which NEC article specifies the requirements for the installation of raceway and enclosure fittings? A) Article 300 B) Article 314 C) Article 330 D) Article 358 Answer: A Explanation: Article 300 deals with general requirements for wiring methods, including fittings. Question 50. A building has a dedicated 240-V, 30-A circuit for an electric water heater. What size copper conductor (AWG) is required for the ungrounded conductors, assuming 75 °C insulation? A) #10 AWG B) #8 AWG C) #6 AWG D) #4 AWG Answer: B
